Heat the olive oil in a large pan. Add the onion and garlic and cook gently for 5 minutes until soft. Add the cumin and paprika and cook, stirring for 1 minute.
Add the tomatoes, stock, cinnamon stick, saffron, eggplants, zucchini, carrots, and season with salt. Bring to the boil, cover, lower the heat and cook gently for 20 minutes until the vegetables are just tender.
Line a steamer or colander with a double thickness cheesecloth. Soak the couscous according to the instructions on the packet.
Add the chickpeas and prunes to the vegetables, stir and cook for 5 minutes.
Spread the couscous in the prepared steamer. Place the steamer on top of the vegetables, cover and cook for 5 minutes or until done.
Stir the herbs into the vegetables. Heap the couscous on to a serving dish. Using a slotted spoon, remove the vegetables from the frying pan and add to the couscous. Spoon over a little sauce and toss gently. Stir the harissa into the remaining sauce and serve separately.